Constipation Flashcards
What is constipation?
It is defined as a condition in which a patient has infrequent bowel movements (<3 a week), often with hard, dry stools that may be painful and difficult to pass.
What are the causes of constipation?
The main causes of constipation that are seen on the surgical ward include:
- Physiological
- Due to factors such as a low fibre diet, poor fluid intake or low physical activity
- Iatrogenic
- Medications such as opioid analgesia, anticonvulsants, iron supplements or antihistamines
- Pathological
- Such as bowel obstruction, hypercalcaemia, hypothyroidism or neuromuscular disease
- Functional
- From painful defecation (such as anal fissures)
Following abdominal procedures, post-operative ileus can also be a common cause in the post-operative setting. Any patient with absolute constipation and associated features of bowel obstruction should be considered as such until proven otherwise
What are the clinical features of contipation?
Constipation can present with lower abdominal pain. In severe cases, patients may also present with abdominal distension, nausea and vomiting or decreased appetite.
Most patients will have no clinical signs on examination; only severe cases are likely to have abdominal distension or tenderness (both secondary to faecal impaction).
A Digital Rectal Examination (DRE) is essential for any patient with constipation to assess the degree of faecal impaction.
What investigations should be ordered for constipation?
Most cases of post-operative constipation are benign in nature and can be made as a clinical diagnosis, with no further investigations required. However any features should suggestive of an underlying sinister pathology will require endoscopy.
If no cause can obviously be identified or it is severe/resistant to treatment, routine bloods (such as TFTs or serum Ca2+) may be requested.
Abdominal X-rays, CT scans, or endoscopies are generally not indicated unless obstruction is suspected. Imaging may indeed show faecal impaction, yet this is not an indication for the image request.
What is shown in the image?
Plain film abdominal radiograph showing constipation in a child; the faecal matter is opaque white, surrounded by black bowel gas.
Briefly describe the pharmacological management of constipation
Laxatives can be used if the patient remains constipated; the choice of laxative depends on suspected underlying cause and stool consistency on PR examination. The major types of laxatives are:
- Osmotic laxatives
- Stimulant laxatives
- Bulk forming laxatives
- Rectal medications
Patients with a hard stool and chronic constipation issues will benefit from a stool-softening laxative, such as movicol or lactulose, but may require glycerine suppositories to help soften the rectal stool initially.
Describe osmotic laxatives
Increase the amount of fluid in the bowel thereby softening stool. e.g. lactulose, movicol.
Describe stimulant laxatives
Stimulate the bowel to contract thus expelling faeces e.g. senna, picosulphate.
Describe bulk forming laxatives
Help stool to retain water thereby softening stool e.g. ispaghula husk.
What medication is used to treat post-op ileus, opioid induced constipation or soft stool?
Patients with post-operative ileus, opioid-induced constipation or a soft stool will benefit from a stimulant laxative, such as senna or picosulphate.
If pharmacological therapy is not effective, what is the next step?
In resistant cases, additional therapy can be given via manual evacuation or an enema.
How can constipation be avoided?
Opioid analgesia should be avoided where possible and other opioid-sparing agents used. Prophylactic stimulant laxatives, such as senna, should be used for patients on opioid analgesia, especially in the elderly.
